$ git clone -n https://src.fedoraproject.org/rpms/R-R.cache.git /var/lib/mock/f45-build-5888-345/root/chroot_tmpdir/scmroot/R-R.cache
Cloning into '/var/lib/mock/f45-build-5888-345/root/chroot_tmpdir/scmroot/R-R.cache'...
$ git fetch origin 40208f4b796a08171c3d647579fe1d1750064256:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-R.cache
 * [new ref]         40208f4b796a08171c3d647579fe1d1750064256 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 40208f4 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild